\begin{tikzpicture}
    \tkzDefPoints{0/0/B, 2/0/C, 1.4/1.4/A}
    \tkzDefPointOnLine[pos=1.5](C,A)  \tkzGetPoint{D}

    \tkzDrawLines[add=0.4 and 0.4, dashed](A,B  B,C  A,C)
    \tkzDrawPolygon(A,B,C)
    \tkzLabelPoints[right](A)
    \tkzLabelPoints[above left](B)
    \tkzLabelPoints[above right](C)
    \tkzLabelPoints[left](D)
\end{tikzpicture}

